Computer systems from their inception have been plagued with the problem of transferring data and sharing resources amongst different hardware configurations. Great inroads have been made in "networking" computers with the emergence of the local area network (LAN). A LAN is a privately owned network that offers reliable high-speed communication channels optimized for connecting computer systems within a limited geographic area such as an office, a building or a cluster of buildings. A LAN expands resource sharing by offering a common standard for communication between equipment of different vendors. A LAN is designed with enough in common to allow vendor-independent exchange of information across user applications and equipment functions. Network architectures created by most vendors conform to the International Standards Organization (ISO) seven-layer model for open systems interconnection (OSI) more fully defined in the Institute of Electrical and Electronic Engineers (IEEE) 802 standard. In the hierarchy of the seven-layer model, the lowest layers, the so-called physical and data link layers, comprise functional modules that specify the physical transmission media and the way network nodes interface to it, the mechanics of transmitting information over the media in an error-free manner, and the format the information must take in order to be transmitted. A typically LAN phase encodes data in a Manchester code format and serially transmits the data over a coaxial type link. The IEEE 802.3 standard specifies the coaxial link to be either a 10Base2 variety or the more popular 10Base5 type, commonly referred to as Ethernet.
A proposed supplement (P802.3I/D10), incorporated herein by reference, to the IEEE standard 802.3, augments the standard for LANs by allowing for a 10Base-T (twisted-pair) media link while maintaining compatibility with the existing data link layer specification. A 10Base-T media attachment unit (MAU) allows existing LANs which conform to the IEEE 802.3 standard to utilize a twisted pair link as its transmission media.
Another traditional problem with computer systems is coping with multiple options available and allowing flexibility between them, such as the option between Ethernet (coaxial) and 10Base-T (twisted pair) type links. Computer hardware with multiple option capability typically requires the user to reconfigure the physical interface by setting switches or jumpers each time a different option is chosen. This approach mandates that the user be knowledgeable at the hardware level in order to take advantage of the multiple option capability.
Therefore, there is a need for providing computer hardware in a LAN, and more specifically a 10Base-T MAU, that automatically responds when activity is present on a twisted pair link, or when such activity is not present, to allow a commonly connected Ethernet (coaxial) type MAU to function in place of the 10Base-T MAU.